Bituminous emulsion and method of making same



patented Jan. 1935 1 BITUMINOUS EMULS ION AND E'rHon oF A H Joseph C. Roediger, Brooklyn; N; assignoi" bi-y mesne assignments, to ThePatent and Licensing Corporation,

ew of Massachusetts N Drawing; Appli 1 Thisinvention relates to aqueous emulsionsof thermoplastic substances and more particularly to soap type emulsionsof such substances as asphalt.

Emulsions of this typeare used for road building or other purposes in which it is frequently necessary to store the material outdoors duringtimes when freezing might occur. 7 l l Thisinvention contemplates the use of 'a-certain emulsifien'which by virtue of its special properties, produces emulsionsthat are resistant to alternate periods of freezing and thawing at temperatures as lowas -40F."

It has'been found that certain rosins'containing, as normally produced, relatively high percentages of unsaponifiable material and natural coloring bodies found in rosins, when saponified,

produce soaps'which maybe used'as emulsifiers in the production of emulsions.

Emulsions produced with this emulsifier under conditions hereduced with equal quantities of such soapsa's are 'm'adefrorn such fatty acids asolein jig'freatei fliiidity thanemulsions of substantially the same average particlesize made withthe fatty acid soaps, and "are ehtir'ely stable when subjected to alter-' hate cycles offreezing and thawing-the freezing being conducted at temperatures as low as 40 E. More specifically, the rosins which "I employin accordance with the invention are the dark; high unsaponifiable' content rosins which are sold, for example," under the w designation of -B. Rosin.

This so-called B Rosin is a 'waste -productfresulting from the process usedin decolorizing rosins. For example, so-called FF Rosin (ruby red in color) is decolorized by being first dissolved in gasoline; a suflicient quantity of furfural is then added. This forms a two liquid layer system in which the furfural layer acts as a selective solvent onthe unsaponifiables and coloring bodies in the original FF Rosin used. After proper treatment the furfural layer is separated and distilled to recover the furfural and the residue remaining is the so-called B Rosin. This 13 Rosin residue contains most of unsaponifiables from the original rosin, and most of the coloring bodies, as well as a good proportion. of the rosin acids.

For example the so-called FFRosin shows an analysis substantially as follows:

Percent Unsaponifiables U Coloring bodies-Jess than l Gasoline insolubles 8 Rosin (as abietic acid) 94 Serial N 6275 inafterm'ore f ullyjdescribe'd,possess the properties of fine average particle size, greater'estabilitytdmech'anicalaction, etc. than emulsions pro- Yf oikjN; X, corporation c ati on ri uguste, 1932" 41 JAftertreatment "such decolorizing: the same, the B Rosin separated fromithe' furfural" layer would have. an. approximateanalysis as follows: v 1' Percent iUn apcnifiab1es 10 to 20 floloring'bodie'si 1 to 2 Gasoline mscmm S g so Rosin (asiabigetic acid) 79 to as The gasoline layer is also distilledrand yields "a yellow rosinicontainingi a small percentage of un- -saponifiables=and aivery'small amount of coloring -bodies'. p biItfisfthusseenvthat the selective solvent action .distributesflthe rosin between the two liquid layers and brings? the main portion of the unsaponiliablesand coloring bodies into the furfural layer.

Theunsaponifiables in this B Rosin are designated aslfresins and are generally considered as beingidifficultlyi'saponifiable esters, high boiling riterpenesandterpene derivativessuch as sesquiterpenes. j

employingithisr:so-called B Rosinfor the manufacture o'fasphalt emulsions of'the type described; itI'is combined with alkali to form a soap wwhichlis then employedv in aqueous solutions of "'certain' concentrations as the emulsifying agent tifOI' the asphalt, the emulsification being conduct- .edflinea standard'i type of l colloid mill. such as a f -Hurren millL' i t 1: -1'rIhave gfound siniaccordance with the invention, ftha'tin' using'the B Rosin as herein described, it is l'ess'ential; if :the' optimum results: and particularly the frost-stability are to be attai'n'eclfthat acertain minimum concentration of the B Rosin soap be present in the aqueous phase, and likewise that limited quantities of excess alkali be employed.

The unsaponifiables contained in theB Rosin become gradually saponified upon long contact with excess alkali. Apparently the character and the amount of the unsaponifiables contained in the B Rosin exert an influence which contributes to the attainment of the desirable properties in an asphalt emulsion made therewith, as above described. This at least is indicated by tests show-- ing that emulsions containing as much as 2% excess alkali on the aqueous phase, in time lose the propertyof withstanding freezings at temperatures of the order of 4 F. followed by thawing without being broken.

For example, various tests on two emulsions of as above described for or two day, freezing cycle. I excessive amounts of free alkalihave the detrivmental effects already described, and in some 6% B Rosin potash soap containing 2.4% of free potassiumhydroxide on the water phase, show the first emulsion to be stable for sixty weeks after undergoing alternate freezing and thawing cycles, whereas the second emulsion showed a break-down after twenty-six weeks of the same type of freezing treatment.

The effect of excessive amounts of excess alkali is even more detrimental in the emulsions made with the sodium soap of B Rosin. For example, a 67% asphalt emulsion having an aqueous phase containing 6.0% of the sodium soap of B Rosin and 0.5% of free, excesssodium hydroxide remained stable to fifty-two weeks of alternate freezings and thawings, whereas a duplicate emulsion containing 1.0% of free excess sodium hydroxide showed break-down after twenty-five weeks of freezings and thawings.

It is extremely important therefore that the amount of excess alkali present in the soap'solution used'for emulsifying the asphalt, be carefully regulated. This excess should be sufficient to re-peptizethe soap upon thawing of the frozen emulsion, but not so large as to react to any substantial extent with the so-called unsaponifiable or coloring body constituents of the rosin soap.

If too little alkali is present, rapid re-peptization of the soap will not take place when the emulsion thaws after having been frozen, and breaking of the emulsion occurs. I have observed that emulsions containing less than 0.1% of free alkali (calculated by weight on the aqueous phase) are not stable to more than four weeks. of freezing and thawing and are usually sufficiently unstable to. show some break-down even in a, one On the other hand,

cases the presence of a large excess of alkali also causes the salting out of the soap and consequent destruction of the ability of the emulsion to withstand the freezing action without detrimental effects.

In general, it may be stated that'the BRosin soap should be present in amounts not less than 3%, and not more than 8%, calculated'by weight on the aqueous phase, since quantities in excess of 8% appear to decrease the frost resistance of emulsions so made. Practice has also shown that asphaltemulsions containing 55% .to 70% of asphalt and 30% to 45% water with a BRosin content of 3% to'8% on the aqueous phase, are the most frost resistant when theaqueous phase contains not less than 0.1% and not'more than 0.5% of free alkali.

I erably potassium hydroxide.

In producing asphalt emulsions of the type herein contemplated, the emulsifying agent may be prepared either by first cooking the B Rosin and the alkali together, or the rosin and alkali may be run hot into the emulsifier together, whereupon emulsification and saponification will take place simultaneously. Thesoap may 'be made by the saponification of the B Rosin with potassium hydroxide, sodium hydroxide, potas-'- sium carbonate or sodium carbonate.

More specifically illustrating the invention, it may be stated that to asphalt content emulsions are being produced by running the proper amount of asphalt (having a melting point of to F. and penetration of to 200) to the colloid mill at a temperature of ZOO-250 F. The B Rosin is saponified with alkali, pref- A Water solution of this soap is made up to yield 4.5-4.8% of B Rosin soap by titration and the free alkali content is adjusted to 0.'l 0;5%. This solution is .runato the colloid mill at a temperature of 100-1l0 F. simultaneously and in a suitable amount with the asphalt, so as to produce an emulsion having 30-35% of water.

This emulsion when subjected to periodic freezing cycles at -4 F. will return to its original condition upon thawing, even after sixty weeks of this treatment. It will also stand several freezing cycles at -.40* LE. without detrimental effects. j

I claim as my invention:

1. A frostproof emulsion of the character described comprising bitumen in the dispersed phase, water in the continuous phase, and from 3 to 8% of B Rosin soap containing 10% to 20% of unsaponifiables as the emulsifying agent, said emulsion containing 0.1% to 0.5% excess of free alkali. 1

2 A frostproof aqueous bituminous emulsion containing from 3% to 8% of B Rosin soap and from 0.1% to 0.5%, of, free alkali calculated on the waterv phase.

. 3..A-frostproof emulsioncomprising approximately 65% to '70% of asphalt, 30% to 35% of water, 4.5% of B Rosin soap and .5% of free alkali, both latter, calculated. on the water phase.

, 4. A frostproof emulsion comprising bitumen the dispersed phase, water in the continuous phase, and 3% to 8% by. weight calculatedon the water phase, of'an emulsifying agent comprising saponified rosin containing 10% to 20% of unsaponifiables, said emulsion containing 0.1% to 0.5% of excess alkali. 4

. JOSEPH C. ROEDIGER. 

